In attitude research, the boomerang effect or negative attitude change id a shift in attitude that not only goes against what was intended but exacerbates people to move in the opposite direction. For example aggressive attempts to get people to change a prejudice may drive them to harden their position.

This is related to "the theory of psychological reactance (that people act to protect their sense of freedom) that is supported by experiments showing that attempts to restrict a person's freedom often produce an anticonformity "boomerang effect" (Brehm, S., & Brehm, J.W. (1981). Psychological reactance: a theory of freedom and control. New York: Academic Press.). For example, after women in Western universities give thought to how traditional culture expects women to behave, they become less - not more - likely to exhibit traditional feminine modesty." (Myers, 2008)

In social marketing, the boomerang effect occurs as a result of attempted attitude change. If someone makes a strong attempt to change a prospect's attitude toward a subject, the prospect will counter with an equally strong response, even if prior to the confrontation, the prospect held a weak attitude toward the subject.

The term "boomerang effect" can be used to describe the effects of a deliberate change to an ecosystem, when these effects escape the control of those who introduced them. Examples include:

The introduction of DDT as a pesticide, which led to the accumulation of the chemical in birds, interfering with their reproduction or killing them.

The introduction of rabbits to Australia by Europeans, which became economically and environmentally damaging, as the rabbits had no natural predators. Then the release of foxes to kill the rabbits, with the foxes instead feeding on the native Australian wildlife.

The draining of American wetlands since colonial times, resulting in flash-flooding and seasonal droughts.

The installation of smokestacks to decrease pollution in local areas, resulting in spread of pollution at a higher altitude, and acid rain on an international scale.